1. Field of the Invention.
The present invention relates to a system for conducting a television audience survey and, more particularly, to a method and apparatus for transmitting channel switch position information from sampled television receivers to a central processing center.
2. Description of the Prior Art.
Television audience rating statistics are very important for broadcasting stations and sponsors. Therefore, it is a common method of collecting these statistics that investigators ask questions of sampled families and collect answers. However, this is a slow and uncertain way of collecting the desired information. As a result, several systems to collect such statistics have been proposed and several kinds of equipment are used.
In the prior art, equipment for conducting a television audience survey consists of recording machines which are attached to television receivers, which recording machines are periodically gathered to read and collect statistics. The recording machines attached to the television receivers include means for detecting the power switch condition and for detecting the channel switch number by identifying the switch angle or the frequency of the receiver local oscillator. Furthermore, means for recording this information on a tape or plate driven by a clock is known.
In these systems, there are several defects in that it is complicated and expensive to record the data within an accurate time and it is expensive and time-consuming to collect the records and manually read them out. Moreover, the reliability of this statistics is degraded because of the absence of samples which are impossible to collect and also because the manual reading out of the data causes errors. It is also a substantial deficiency that collecting the data and reading and calculating it takes a long time so that the results of the survey do not respond quickly to sponsors or television broadcasting stations.
Furthermore, television receivers are now very common and many families have plural television receivers. In these cases, the prior method, which is based on a single receiver, does not always show suitable statistics of all of the television receivers which broadcasting stations and sponsors desire.